1. Field of the Invention
This invention relates to a method and apparatus for inhibiting inadvertent initiation of a munition.
2. Description of Related Art
Energetic materials, such as explosives and propellants, are often found in confined spaces within munitions. Under normal conditions, these materials are unlikely to detonate or burn spontaneously; however, many are sensitive to heat and mechanical shock. For example, when exposed to extreme heat (as from a fire) or when impacted by bullets or fragments from other munitions, the energetic materials may be initiated, causing the munitions in which they are disposed to inadvertently react at a rate ranging from slow burning to detonation.
Efforts have been made to develop insensitive munitions, which are munitions that are generally incapable of detonation except in its intended mission to destroy a target. In other words, if fragments from an explosion strike an insensitive munition, if a bullet impacts the munition, or if the munition is in close proximity to a target that is hit, it is unlikely that the munition will detonate. Similarly, if the munition is exposed to extreme temperatures, as from a fire, the munition will likely only burn, rather than detonate.
One way that munitions have been made more insensitive is by developing new explosives and propellants that are less likely to be initiated by heating and/or inadvertent impact. Such materials, however, are typically less energetic and, thus, may be less capable of performing their intended task. For example, a less energetic explosive may be less capable of destroying a desired target than a more energetic explosive. A less energetic propellant may be capable of producing less thrust than a more energetic propellant, thus reducing the speed and/or the range of the munition. Additionally, the cost to verify and/or qualify new explosives and/or propellants, from inception through arena and system-level testing, can be substantial when compared to improving the insensitive munition compliance of existing explosives and/or propellants.
Other development efforts have resulted in devices that are designed to vent pressure within the munition in the event the munition is exposed to a fire. Some such devices, known as the thermally initiated venting systems, include an external thermal cord which, when ignited, triggers an out-of-line device that, in turn, detonates a linear shaped charge. The detonation of the linear shaped charge weakens the housing containing the munition's energetic material, allowing the energetic material to vent without exploding. However, such thermally initiated venting systems do not address other insensitive munitions issues, such as bullet impact, fragment impact, and slow heating (i.e., “cook-off”) of the energetic material.
The present invention is directed to overcoming, or at least reducing, the effects of one or more of the problems set forth above.